Series 6​

​This series was printed by the Royal Thai Survey Department and the Naval Hydrographic Department. There were 2 denominations, and each denomination had two types. The 20 baht denomination had similar features as the 4th series printed by Thomas De La Rue & Company Limited and the 100 baht denomination had similar features as the 4th series printed by the Royal Thai Survey Department using paper from Thai paper mill in Kanchanabury. They had been issued in 1945.​